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RE: [PATCH] printk: introduce kptr_restrict level 3

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> -----Original Message-----
> From: Christoph Hellwig [mailto:hch@infradead.org]
> Sent: Thursday, October 6, 2016 9:32 AM
> To: Roberts, William C <william.c.roberts@intel.com>
> Cc: kernel-hardening@lists.openwall.com; corbet@lwn.net; linux-
> doc@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] printk: introduce kptr_restrict level 3
> 
> On Wed, Oct 05, 2016 at 02:04:46PM -0400, william.c.roberts@intel.com wrote:
> > From: William Roberts <william.c.roberts@intel.com>
> >
> > Some out-of-tree modules do not use %pK and just use %p, as it's the
> > common C paradigm for printing pointers. Because of this,
> > kptr_restrict has no affect on the output and thus, no way to contain
> > the kernel address leak.
> 
> So what?  We a) don't care about out of tree modules and b) you could just triviall
> fix them up if you care.

Out of tree modules still affect core kernel security. I would also bet money, that somewhere
In-tree someone has put a %p when they wanted a %pK. So this method is just quite error
prone. We currently have a blacklist approach versus whitelist.

> 
> No need to bloat the kernel with crap like this.

It's unconstructive comments like this that do the whole community harm. Notice how
responses from Kees Cook were aimed at finding a different solution to the problem and were
very constructive. As far as "bloating" goes, it really didn't change a whole lot, most of it was moved
lines, and adds maybe a few lines of code.

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[PATCH] printk: introduce kptr_restrict level 3 william.c.roberts@intel.com - 2016-10-05 20:10 +0200
  Re: [PATCH] printk: introduce kptr_restrict level 3 Kees Cook <keescook@chromium.org> - 2016-10-05 21:40 +0200
    RE: [PATCH] printk: introduce kptr_restrict level 3 "Roberts, William C" <william.c.roberts@intel.com> - 2016-10-06 15:20 +0200
  Re: [PATCH] printk: introduce kptr_restrict level 3 Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-10-05 23:00 +0200
    RE: [PATCH] printk: introduce kptr_restrict level 3 "Roberts, William C" <william.c.roberts@intel.com> - 2016-10-06 15:30 +0200
  Re: [PATCH] printk: introduce kptr_restrict level 3 Christoph Hellwig <hch@infradead.org> - 2016-10-06 15:40 +0200
    RE: [PATCH] printk: introduce kptr_restrict level 3 "Roberts, William C" <william.c.roberts@intel.com> - 2016-10-06 15:50 +0200
      Re: [PATCH] printk: introduce kptr_restrict level 3 Christoph Hellwig <hch@infradead.org> - 2016-10-06 16:00 +0200
        RE: [PATCH] printk: introduce kptr_restrict level 3 "Roberts, William C" <william.c.roberts@intel.com> - 2016-10-06 17:10 +0200
        Re: [PATCH] printk: introduce kptr_restrict level 3 Kees Cook <keescook@chromium.org> - 2016-10-06 23:10 +0200
          Re: [PATCH] printk: introduce kptr_restrict level 3 Joe Perches <joe@perches.com> - 2016-10-06 23:30 +0200
            Re: [PATCH] printk: introduce kptr_restrict level 3 Kees Cook <keescook@chromium.org> - 2016-10-06 23:30 +0200
          RE: [PATCH] printk: introduce kptr_restrict level 3 "Roberts, William C" <william.c.roberts@intel.com> - 2016-10-07 16:30 +0200
      Re: [kernel-hardening] RE: [PATCH] printk: introduce kptr_restrict  level 3 Jann Horn <jann@thejh.net> - 2016-10-06 16:10 +0200
        Re: [kernel-hardening] RE: [PATCH] printk: introduce kptr_restrict  level 3 Jann Horn <jann@thejh.net> - 2016-10-06 16:50 +0200
        Re: [kernel-hardening] RE: [PATCH] printk: introduce kptr_restrict  level 3 Jann Horn <jann@thejh.net> - 2016-10-07 14:00 +0200

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